GENOA, Italy -- It's Wednesday afternoon, a time when Genoa's main avenue is normally bursting with shoppers and cars.

But these aren't normal days in the northern Italian city, and on the sprawling Via XX Settembre a petite dark-haired lawyer named Giulia Orlando is the only civilian in sight. Fearing riots and terror attacks as leaders of the world's eight main industrial democracies converge on Genoa this weekend, Italian...